| 摘要 |
PURPOSE:To execute moving speed control of a movable mirror with high accuracy, and also to make a device low in cost and to make same device long in life by providing a frequency/ voltage converting means, a voltage difference detecting means for comparing the voltages and outputting its difference, a phase comparing means for generating a signal of an output corresponding to a phase difference, and a control means. CONSTITUTION:A coil 16 moves in the axial direction together with a hollow cylindrical body 15 by the same theory as a moving coil type loudspeaker, by a current flowing to the coil 16 being a driving source, a movable base 12 connected to its hollow cylindrical body 15 moves linearly in a state that it is supported and guided by a supporting and guiding means such as a roller bearing, etc., and a movable mirror 4 moves continuously in the direction falling at right angles to a main mirror surface 4A and an auxiliary mirror surface 4B. In an auxiliary Michelson's interferometer 20 containing the auxiliary mirror surface 4B formed on the rear side of the movable mirror 4, basing on an interference fringe by light of a specified wavelength, an AC signal of a frequency corresponding to a moving speed of the movable mirror is outputted from a photodetector 24 by movement of the movable mirror 4. An output signal of this photodetector 24 is inputted to a driving control part 25, and a driving current of the coil 16 as functioning a driving source is brought to feedback control. |
